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Questions tagged [obd-ii]

On-Board Diagnostics-II (OBD-II). Questions usually involve scan tools, their use and their compatibility, as well as how to interpret Diagnostic Trouble Codes (DTCs).

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33 votes
12 answers
83k views

Can a vehicle be harmed with bad inputs via an OBD-2 port?

I bought a cheap (sub $10) ELM 327 Bluetooth clone OBD-2 diagnostic adapter on a local "ebay-style" market where the seller specializes in car diagnostics and has several thousand positive reviews (...
Kozuch's user avatar
  • 1,305
32 votes
2 answers
70k views

Difference between OBDII and CAN

What is CAN (controller area network)? What are the differences between an OBD-II protocol and a CAN setup?` How do I use an OBD-II scanner on a vehicle with CAN?
Shobin P's user avatar
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22 votes
3 answers
77k views

Can OBD-II be used to control the vehicle?

Is the OBD-II port in vehicles only used for reading diagnostic codes or is there some functionality that allows the vehicle (eg. engine revving) to be controlled through OBD-II? Thanks.
Bert Wagner's user avatar
22 votes
3 answers
1k views

What are good features to look for in an OBD-II reader

I recently took my car in for the engine light. It turned out to be a minor problem (crack in gas cap let water in). It would be nice to have a low-cost OBD-II reader to be able to find out for ...
Brian Carlton's user avatar
20 votes
3 answers
515k views

What is the pin or keycode for ELM327 bluetooth OBDII adapter?

The infamous ELM327 OBDII device came without any paper, just a crappy CD with no document related to the device (only some software and drivers thrown on the CD almost randomly). I tried the ...
sorin's user avatar
  • 545
17 votes
4 answers
145k views

What iPhone/iPad app works best with ELM327 Bluetooth OBD-II reader?

I've found a number of apps for the iPhone/iPad that connect to ODB-II readers via WiFi, but unfortunately that means that it disables 3G and all the benefits of having a 3G device built into my dash. ...
Chase Florell's user avatar
17 votes
5 answers
88k views

What is the motorcycle equivalent of OBD-II?

I once met an OBD-II expert while traveling and asked him if motorcycles (especially the fuel-injected ones) employ a similar protocol. He said that the use of such a protocol is not as widespread ...
Zaid's user avatar
  • 39.2k
16 votes
3 answers
1k views

What to know before buying and OBD-II reader

I read the features to look for in an OBD-II reader, but I am curious if getting one is the right move. I'm just planning to get a cheap one, which is proving to be interesting shopping local. What I ...
Jim McKeeth's user avatar
16 votes
1 answer
4k views

How do I find the correct pins in a CAN-BUS connector?

This question might be too technical for this forum, but I'll give it a go. I have a 2012 BMW R1200R motorcycle with CAN-BUS. I'd like to make an Arduino interface to the connector on the bike, but I ...
Eric Fossum's user avatar
13 votes
1 answer
8k views

How to detect engine/ignition (on/off) status using OBD2?

My device needs to know when a car engine/ignition is started and stopped. Is it possible to get that status using OBD2? If yes, which PID will give me that information? Do I need to write any car-...
rp1980's user avatar
  • 325
12 votes
2 answers
4k views

Why do we need make-specific cables to read car ECUs?

I find it bizarre that the automotive industry has standardized the use of the OBDII protocol, yet most cars require make-specific cables in order to access the complete set of diagnostics and ...
Zaid's user avatar
  • 39.2k
12 votes
2 answers
5k views

Received frames from vehicles with multiple ECU chips

I'm not generally a 'car person', so hopefully I can explain this well enough to get some help here: When sending messages to an OBD-II device, I receive one response in most cars I've tested. ...
Rein's user avatar
  • 221
11 votes
8 answers
5k views

What is the point of performing an OBD2 diagnostic scan if there is no malfunction indicator?

Where I live, it is common for car mechanics to help their customers who are planning to purchase a new used car by performing an OBD2 diagnostic test on the car in question, even if there are no ...
hb20007's user avatar
  • 735
11 votes
4 answers
16k views

Controlling door locks via CAN bus

I'm trying to figure out how to lock and unlock the doors of a 2010 Toyota RAV4 using the CAN bus via the OBD-II port. I have a microcontroller attached via an CAN controller and a CAN receiver, and I'...
Isvara's user avatar
  • 261
11 votes
3 answers
117k views

Do fault codes get recorded with a time stamp into a log with a history of DTCs?

Just scanned my vehicle for the first time to check out the code for a Check Engine Light. I grew curious if these fault codes get logged somewhere with a date and time stamp of some kind at the time ...
jxramos's user avatar
  • 1,860
11 votes
1 answer
506 views

Are there any plans to update OBD-II?

OBD-II is ancient It predates the Porsche 911 GT1, Windows 95 and implementation of the Schengen Agreement. I would have thought that SAE would be working to add more diagnostic coverage for ...
Zaid's user avatar
  • 39.2k
10 votes
4 answers
26k views

Is control module voltage and battery voltage the same?

Is the Control Module Voltage (from OBD Mode 01 PID 42) and battery voltage the same? If not, what is the relation between them? Why is the max value of Control Module Voltage (from OBD Mode 01 PID 42)...
Soumya Sen's user avatar
  • 1,521
10 votes
4 answers
24k views

Controlling door lock/unlock via CAN bus

I'm trying to figure out how to lock and unlock the doors of a 2016 Mercedes Citan using the CAN bus via the OBD-II port. Is there some kind of OBD-II interface where I can control this with plain ...
Sebastian Breit's user avatar
10 votes
3 answers
2k views

How do I get to see my Mode 06 in OBDii

Mode 06 in OBD2 is good to get an insight of what faults the car might encounter in the future. But I am unable to find out what command should I send to get Mode 06 data. It has TID$01 CID$01, so how ...
Soumya Sen's user avatar
  • 1,521
10 votes
2 answers
1k views

Computing Wheel Torque From Engine Torque

It seems possible to obtain engine torque and RPM from a truck CAN bus. I'd like to estimate tractive force at the wheels given these two values. How should I go about computing torque at the wheels? ...
user1889776's user avatar
9 votes
4 answers
32k views

Disabling OBD2-Interface in a car

If a car-thief wants to steal a modern car, he often uses the OBD2 (On Board diagnosis) to "hack" the car. Simplified: He achieves this by plugging his "hacking device" in the port, which aquieres ...
Michael B's user avatar
  • 287
9 votes
2 answers
2k views

How do I go about troubleshooting DTC codes?

When the check engine light (CEL) comes on, there is usually a diagnostic trouble code (DTC) that can be read from the OBD-II (onboard diagnostic) port on modern codes. How do I go about using the ...
dlu's user avatar
  • 14.5k
9 votes
2 answers
910 views

OBDII across the world?

Is OBDII consistent across the world? Any vehicle sold in North America particularly in the United States must conform exactly to all OBDII rules. What about vehicles that are sold in the US but ...
vini_i's user avatar
  • 16k
9 votes
1 answer
7k views

Is it possible to auto close the power window of a car using OBD and CAN bus?

I am not an electrical or automobile engineer, so pardon my ignorance. I found this product in the market to auto close power windows for certain brands. How can we send signals to the CAN bus using ...
rp1980's user avatar
  • 325
9 votes
1 answer
4k views

ATMA on OBDII not Working

I have successfully connected a terminal android app to the obd port of my car. And tried dry run of many at commands, many are working as expected. But ATMA (AT command to Monitor All) is not ...
vinay's user avatar
  • 221
9 votes
2 answers
13k views

Is it Possible to Control Lights through OBD-II Port?

Is it possible to use a car's onboard diagnostic port to toggle the headlights, interior lights, or parking lights? If not through the OBD-II port, how would I go about remotely toggling the lights on ...
Matthew's user avatar
  • 193
9 votes
2 answers
20k views

What's the Difference Between OBDII adapters and Toyota Mini VCI?

I've been researching Toyota diagnostic connectors, and ran across something called a Mini VCI adaptor meant for use with Toyota's TechStream software. The physical interface looks like a standard ...
Robert S. Barnes's user avatar
9 votes
1 answer
48k views

Can I use an OBD2 Scan Tool on older GM vehicle?

I can get an adapter that connects my OBD2 scan tool to my 12 pin GM scan tool connection. But will the tool be able to read the codes and tell me anything useful? Or do I need to get a scan tool that ...
Jim's user avatar
  • 248
8 votes
2 answers
15k views

OBD-II difference between signal ground and chassis ground

Am planning to install a carputer (Raspberry Pi) in a 2005 Ford Mondeo, replacing the car stereo. The Quadlock connector to the stereo apparently includes CAN bus, so I am thinking I will get a USB ...
Tomas By's user avatar
  • 215
8 votes
2 answers
5k views

2000 chevy cavalier cheap upgrades

I am a high schooler that was lucky enough to get a 2000 chevy cavalier 2.2l automatic 4 door sedan for $100 for my 16th birthday. One of the parents owns a drag strip/race track that we can use, so ...
Alex Rodgers's user avatar
8 votes
1 answer
12k views

Would OBD-II devices drain the battery when used 24/7?

There are many OBD-II devices out there that can scan and/or monitor real-time data about your car. Most of these devices are readable via USB or Bluetooth. Either USB or Bluetooth, both require some ...
Abel Melquiades Callejo's user avatar
8 votes
2 answers
94k views

OBD II power when key not in ignition

I can't get to the OBD connector on my car at the moment. As far as I know the OBD II voltage is active even when the key is in lock. Can anyone confirm this? edit : It's for a product that will be ...
SeanJ's user avatar
  • 533
8 votes
1 answer
2k views

How much battery does an ODB Bluetooth reader suck?

I'm planning on using an ODB Bluetooth reader on my car and leaving it plugged in to use apps like Dash and Torque. It's a daily driver so I'm not that worried about depleting the car's battery, but ...
Duccio Shinichi Mondanelli's user avatar
8 votes
4 answers
11k views

shop can't connect to onboard diagnostic system?

I've recently moved to California and am trying to get my car registered; they require a smog check (which is possibly actually more of an inspection than the name implies?). I went by a very basic ...
Cascabel's user avatar
  • 181
8 votes
2 answers
51k views

'Check Engine' code P0171 System Too Lean - Is it safe to drive?

My 2003 Toyota Corolla's Check Engine Light came on. I read the codes using an OBD code reader and got P0171 - System Too Lean (Bank 1) and P0133 - 02 Circuit Slow Response (Bank 1, Sensor 1). The ...
culix's user avatar
  • 301
8 votes
3 answers
6k views

Calculating MPG from MAP sensor (or converting MAP data to MAF data)

My 2002 Honda Accord V6 has a Manifold Absolute Pressure sensor (MAP). I understand that this sensor gives out information in pressure units (psi or equivalent). After doing a bit of research, I ...
NewGradDev's user avatar
8 votes
1 answer
2k views

Does OBD II explicitly or implicitly include forward/reverse information?

From my understanding, OBD II does not directly tell if a car is in forward or reverse gear. I wonder what the best way to derive such information from OBD data if there is any. Following the ...
sma's user avatar
  • 181
8 votes
3 answers
9k views

Can a check engine light reset itself when a scan tool is connected?

I have a Toyota RAV4 2002 4WD. I was driving to the car wash when suddenly the check engine light come on when I accelerated hard. After the wash, it still was on. I drove home, shut it off, turn it ...
Major Stuen's user avatar
8 votes
1 answer
1k views

OBD Accessory External Power Supply

I recently purchased the Zubie Car Hotspot from Verizon that connects to the OBD port on a car. I have mine connected to the Tesla Model X, unfortunately I need the connection to remain always on but ...
MTG's user avatar
  • 81
7 votes
2 answers
17k views

Should I replace my own oxygen sensor if i have a Check Engine Light and Code P2195?

My 2003 focus lx 2.0L L4 SOHC ~18,000 miles has had the engine light so i went to autozone to read the code. Autozone obd2 printout says "P2195 lack of heated oxygen sensor- Bank 1 Sensor 1 HO2S11 ...
catjacent's user avatar
  • 141
7 votes
1 answer
4k views

What does it mean when the ELM327 OBD2-reader gives two lines of info for 0100 request?

I have an ELM327-based OBD2 reader that I can issue commands to when connected to a car. I'm running this on a 2015 Acura RDX. When I issue the request 0100 to get supported mode 1 PIDs, I get the ...
Ana's user avatar
  • 171
7 votes
2 answers
5k views

Is it possible to access multiple CAN buses through the OBD-II port?

As usual I apologize if this has been asked and answered somewhere. I try to only ask questions if I can't find an answer or a satisfactory answer. From my understanding the OBD-II port on vehicles ...
Moeman69's user avatar
  • 393
7 votes
2 answers
1k views

What is the point of a vacuum pump with a fuel injection engine?

I recently got an OBD-II dongle with the Torque Android app, which allows me to read the computer's output in real time. The app will let me drag and drop different gauges on my screen, which works ...
Rubber Duck's user avatar
7 votes
5 answers
4k views

Are there any OBD II converters on the market?

I know there are tons of readers and software on the market, but what I really need is something to convert signals of my1970s sensors (fuel level, speed, coolant temp, etc) to OBD compliant signals. ...
Kilhoffer's user avatar
  • 209
7 votes
1 answer
22k views

Is Torque App reliable to read O2 sensor data?

My 2006 Toyota Prius is throwing code P0420 and I used a cheap OBD-II reader with Torque App on Android to check if my O2 sensors are working or not. I tried the maintenance mode to just run the ...
Gabriel Diego's user avatar
7 votes
2 answers
1k views

control car's steering angle from linux

I'm trying to send steering wheel angle commands to my car. It's a fairly recent car (Renault Espace IV). I'm using an OBD2 port to access it, and I also have a ShieldCan. I managed to read data from ...
Graham Slick's user avatar
7 votes
1 answer
3k views

Erratic single fault code: P0420, P0440, P0446. Normal variance, or indicative of something deeper?

Working on diagnosing an evap/emission/fuel system problem on my Toyota 2003 Corolla. More on that in this question. On 3/2, I saw a mechanic use his handheld OBD to read a code P0420. On 3/12, ...
bishop's user avatar
  • 871
7 votes
1 answer
590 views

2008 Chrysler Crossfire - Check Engine Light

My check engine light has been on for quite sometime. I was hoping maybe somebody on the forum can give me a few pointers on what to look for. Even though the light is on, the car is running better ...
user3496471's user avatar
6 votes
3 answers
1k views

Tapping into the on-board computer

I'm thinking of replacing my car's radio panel with a custom built Raspberry Pi device, something like this device. However, it's usefulness would be much larger, if I could get information from the ...
Petr's user avatar
  • 235
6 votes
2 answers
15k views

Any open-source OBD scanner analysis tools?

I've been having some weird problems with my '06 Pontiac G6, and finally broke down and bought a Bosch code scanner to see if the DTCs could tell me anything... they didn't. This scanner has the ...
Matt's user avatar
  • 609

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